Such a heat exchanger is known from U.S. Pat. No. 7,490,660 B2. The gasket has a recess which fits to the protrusion. At the side facing the adjacent heat exchanger plate the gasket has a protrusion fitting in a recess which is formed on the lower side of the adjacent heat exchanger plate. The recess is the negative form of the protrusion on the upper side of the adjacent heat exchanger plate.
The space between the heat exchanger plate and the adjacent heat exchanger plate forms part of the primary flow path or part of a secondary flow path through the heat exchanger. The gasket seals the flow path from the outside or in the region of supply and return openings of the heat exchanger plates from the other flow path.
In order to achieve a good heat transfer from one flow path to the other flow path the heat exchanger plates are relatively thin. This causes a problem in that the pressure of the fluid within a flow path may deform the heat exchanger plate. This is especially the case in the area around the openings forming a supply or a return opening, respectively, of the respective flow paths. In the region of these openings, there is in many cases no sufficient connection between a heat exchanger plate and the adjacent heat exchanger plate.
The solution disclosed in U.S. Pat. No. 7,490,660 B2 helps to keep the gasket in position, i.e. between the groove of the heat exchanger plate and in the recess of the adjacent heat exchanger plate. Furthermore, the sealing line has been made longer than without the recesses and protrusions. However, when the heat exchanger plate deforms under the pressure in one of the flow paths, there is still the risk of a leakage when the heat exchanger plate is lifted off the gasket. In this case an opening may appear between the recesses and the gasket, thus giving leaks.